The ability to manipulate the mouse genome through transgenic and knock-out or knock-in technologies[unreadable] has revolutionized modern Immunology. The purpose of this core facility (Core B) is to integrate the[unreadable] transgenic and gene targeting approach into the studies of host-pathogen interaction, a major thrust of the[unreadable] program project "Mouse models for understanding host-pathogen interactions". This[unreadable] Transgenic/Knockout Mouse Core will provide the critical technical capability to generate and to maintain[unreadable] transgenic and mutant mice commonly used by two or more investigators of the program project (PPG).[unreadable] In particular, this Core will complement Core C to provide transgenic mice expressing fluorescent proteins[unreadable] to be used for imaging studies. Core B will also generate and distribute transgenic strains of mice as[unreadable] needed by the individual investigator in the PPG. In aim 1, C57Bl/6 transgenic mice expressing[unreadable] fluorescent genes, whose expression is driven by different promoter/enhancers will be generated and[unreadable] maintained for use in video imaging experiments. These include mice expressing membrane Cyan[unreadable] Fluorescent Protein (CFP) in dendritic cells or macrophages and mice with CFP or YFP (Yellow[unreadable] Fluorescent Protein) expressed in all cell types. In aim 2, knock-out/knock-in mice with genes involved[unreadable] in innate immunity will be maintained as well as back-crossed to C57BI/6 or Balb/c if necessary. These[unreadable] mice, including DC- and macrophage-specific FADD-/-, MyD88-/-, IFN-alpha/betaR-/-, TRAIL-R-/-, NK deficient[unreadable] mice, NKG2D-/-, IL-12/GFP (Green Fluorescent Protein) knock-in and lFN-gamma/GFP knock-in mice, will be[unreadable] provided to investigators in the PPG for their biochemical, infection or imaging experiments. In aim 3,[unreadable] Core B will generate and provide transgenic mice for the specific needs of the individual PPG[unreadable] investigator. Completion of these aims is necessary and essential for the success of the PPG designed to[unreadable] understand how the immune system interacts with model pathogens.